1. of, relating to, or denoting the geological era between the Paleozoic and Cenozoic eras, lasting from about 252 to 66 million years ago
Usage: geology; often capitalized

1. the Mesozoic era or the rocks and fossils formed during this time period
Usage: geology; often capitalized

Examples

• The Mesozoic era is famous for the dominance of dinosaurs.
• Mesozoic rocks contain abundant fossils of ancient reptiles.
• During the Mesozoic, the continents were arranged very differently than today.
• Paleontologists study Mesozoic deposits to understand prehistoric life.
• The Mesozoic era ended with a mass extinction event 66 million years ago.
• Mesozoic sediments in this region reveal a shallow ancient sea.